1. Technical Field
This invention relates to devices for melting coal tar and like materials.
2. Description of the Prior Art
No devices are known in which coal tar, coal tar enamels, sulphur, asphalt and similar materials have been rapidly and efficiently heated while being simultaneously agitated and conveyed through a tank-like structure. A number of prior art devices have utilized various configurations of coils arranged about a rotatable shaft and wherein the coil configurations are heated or cooled. See for example U.S. Pat. Nos. 313,430, 930,786, 1,717,465, 2,271,862, 2,540,250, 2,594,142 and 3,272,649.
The first of the above-mentioned patents discloses a beer mash tub in which a plurality of coils are mounted on a horizontally disposed shaft and steam is supplied to the several coils so as to stir and cook the mash.
U.S. Pat. No. 930,786 also has a plurality of coils on a horizontal shaft and like the first mentioned patent arranges the coils in unusual configurations with a number of sections arranged in radially spaced relation to one another.
U.S. Pat. No. 1,717,465 discloses a heated helical coil, the convolutions of which are widely spaced and supported by a plurality of cross arms, all for the purpose of heat treating animal offal.
U.S. Pat. No. 2,271,862 discloses a pasturizing device having a pair of coils positioned in spaced relation to one another and around a tubular member through which a heating fluid is selectively communicated with the several coils, pasturization of fluids such as milk and cream being specified.
U.S. Pat. No. 2,540,250, U.S. Pat. No. 2,594,142 and U.S. Pat. No. 3,272,649 all relate to devices for crystalizing sugar syrups, such as sucrose, and these patents disclose the use of various coil configurations in communication with a rotating shaft for heating individual coil convolutions by a heating fluid directed through the supporting shaft. None of the prior art patents disclose the novel concept of arranging a single helical coil with slightly spaced configurations, providing means for heating the same uniformly and for directing pieces of solid material thereinto capable of being liquified by heat supplied the helical coil by hot oil circulated therethrough and simultaneously conveying the pieces of the material longitudinally of the coil as the same are being melted, all as disclosed in the present invention.